Many modern vehicles are equipped with one or more wireless control modules that communicate with a remote message transmission facility such as a “call center”. The most prevalent wireless control module is a so-called “telematics” module that communicates with a remote call center by way of a cell phone network. In addition to supporting voice communications, a telematics module is frequently configured to transmit and receive digital data, even when the vehicle is inactive. For example, the telematics module can be configured to receive vehicle control commands from the call center for activating certain electrical components of the vehicle for unlocking the doors, sounding the horn or flashing the headlights when requested by the vehicle owner or other authorized person.
Wireless modules designed to be operational when the vehicle is inactive are typically assigned a “current budget” at vehicle turn-off in order to prevent excessive power consumption during prolonged periods of vehicle inactivity. A commonly employed power-saving technique places the module in a “sleep” (minimum power consumption) mode at vehicle turn-off, which is occasionally exited when a “wake-up” event occurs. Ordinarily, the wake-up events occur periodically, such as once every five minutes, at which time the module checks for an incoming message from the remote call center. The module services any received messages, deducts the current budget for the power consumed, and then returns to the sleep mode. This process of periodically waking-up and then returning to the sleep mode continues until the vehicle is re-started or the current budget is reduced to zero.
Telematics modules perform as desired except when the vehicle is parked in a location that is not adequately served by the cell phone network. In such instances, communications from the call center cannot be reliably received, and the remote vehicle control functionality is lost. This occurs even when the vehicle is equipped with other wireless control modules such as a satellite digital audio receiver (SDAR) module. Accordingly, what is needed is a communication control method for fully utilizing the communication capability of a vehicle during periods of inactivity.